Fix stack count variable in app.py

- Updated the variable name from 'player_count_var' to 'stack_count_var' to accurately reflect its purpose in the stack frame calculations.
- This change enhances code clarity and ensures the correct tracking of stack counts in the application.

app.py

@@ -321,7 +321,7 @@ with tab2:
                             st.session_state['stack_frame'] = set_frame
                         else:
                             st.session_state['stack_frame'] = pd.merge(st.session_state['stack_frame'], set_frame, on='Stack', how='outer')
-                        player_count_var += 1
+                        stack_count_var += 1
                     st.dataframe(st.session_state['stack_frame'].
                         sort_values(by='Exposure Overall', ascending=False).
                         style.background_gradient(cmap='RdYlGn').